Fender



April 28, 1970 'RYOSUKE KIKUKAWA ET AL 3,508,744

FENDER Filed Sept. 10, 1968 5 Sheets-Sheet 1 RYOSUKE KIKUKAWA FUMIYA HAMATANI MASAYOSHI KUWABARA AKIHISA MORI INVENTORS RNEYS April 28, 1970 RYOSUKE KIKUKAWA ET AL 3,503,744

FENDER Filed Sept. 10, 1968 3 Sheets-Sheet 2 F/G-4A Strcin, in percent of the original height %a b ga d L I/I c Stroin, in percent of the original height F/G-4B RYOSUKE KIKUKAWA FUMIYA HAMATANI MASAYOSHI KUWABARA AKIHISA MORI NVENTORS l 1970 RYOSUKE KIKUKAWA ET AL 3,508,744

FENDER Filed Sept. 10, 1968 3 Sheets-Sheet 5 RYOSUKE KKUKAWA FUMIYA HAMATANI MASAYOSHI KUWABARA AKIHISA MORI INVENTORS United States Patent Ofiice 3,508,744 Patented Apr. 28, 1970 U.S. Cl. 267-1 4 Claims ABSTRACT OF THE DISCLOSURE An arch-shape fender having a lateral cross section comprising an elongated shock-receiving portions, located at the top of the cross section, a pair of mounting portion located at the bottom of the cross section, and a pair of shock-absorbing portions extending between said shock-receiving portion and said mounting portions. Each shock-absorbing portion has a buckling point located away' from said mounting portion by 0.4H to 0.8H, H'being the distance between the pair of mounting portions.

This invention relates to a fender, more particularly to a fender to be mounted on quay walls for protecting both the ship side board and the quay wall from mechanical shocks, by absorbing kinetic energy of the ship, when the ship is going to abut on the quay for mooring.

An Object of the present invention is to provide a fender made of rubber and rubber-lke elastic material and having highly stable operative characteristics with a large energy absorbing power for an intermediate magnitude region of reactive force produced therein.

When a ship of mass M is going to abut on a quay at a velocity of V, the kinetic energy E of the ship is given by E=( /2)MV In other words, the larger the mass M and the Velocity V are, the greater the kinetic energy will be. Such kinetic energy should be completely absorbed by the contraction of the fender body made of rubber and rubber-like elastic material mounted on the quay wall and the buckling of fender holders holding the fender body at opposite ends thereof. As a result of it, the ship is prevented from directly striking the quay, so that damages on both the quay wall and the ship, or at least on either one of them, can be mitigated. Strictly speaking, the ship is repelled from the quay by the reactive force generated in the fender and then pushed toward the quay again by the movement of water, and such reciprocative movement of the ship away from and toward the quay is gradually diminished, until the ship comes into complete stop in contact with the quay.

From the standpoint of protecting both the ship and the quay wall, the fender is required to produce as small a reactive force as possible for a mechanical shock of given magnitude, and to have as large as energy absorbing' power as possible. Furthermore, the fender should have high workability and high durability, and should be inexpensive to'manufacture. More particularly, the fender should be easily manufacturable and readily mountable on quay walls, and should have a high resistance against various operative i conditions.

Known fenders for the aforesaid purposes include a cylindrical fender of rectangular cross section and a cyliidrical fender of circular cross section. The known fenders have a disadvantage in that the location of those portions of fender holders holding each fender at opposite ends thereof, which are to be buckled upon the strike by the ship, cannot be assigned defintely, and that if the buckling of the fender holders at the opposite ends of the fender takes place in an unbalanced manner, the

effects of the fender holder buckling are also unbalanced. Thus, the operative characteristics of the known fenders are not stable. Furthermore, the cylindrical construction of the known fenders does not allow the use of large buckling stroke of the fender holders. Accordingly, the magnitude of the reactive force becomes large to reduce the amount of energy to be absorbed by the buckling. The known cylindrical fenders of circular cross section produce`small reactive force, as long as the mechanical shock is small, and the amount of energy to be absorbed by such cylindrical fenders is small, and hence, if a ship is subjected to an eXcessively large shock, the cylindrical fender produces a large reactive force acting on the ship. In addition, for vulcanizing the known fenders made of cylindrical members, it is necessary to use a core to be secured to metal molds only at extreme ends thereof. Thereby, there is a danger that the thickness of the cylindrical member at one end thereof may differ from the corresponding thickness of the opposite end thereof. Such unbalance in the thickness of the cylindrical fender has often caused the aforesaid unbalanced buckling of the fender holders.

The fender, according to the present invention, has an arch-shaped lateral cross section comprising a shock-receiving portion, a pair of mounting leg portions disposed symmetrically with respect to said shock-receiving portion, and shock-absorbing portions interconnecting said mounting leg portions to said shock-receiving portion, said shock-absorbing portions having buckling points disposed on the inside surface thereof, whereby the kinetic energy of ship Striking the fender can be absorbed by the buckling of the fender at a high rate while generating only a small reactive force. With such construction, the fender of the present invention has stable load-strain characteristics.

For a better understading of the invention, reference is made to the accompanying drawings, in which:

FIG. 1 is a top view of a fender, embodying the present invention;

FIG. 2 is a sectional view, taken along the line 2-2 of FIG. 1;

FIGS. 3A and 3B are enlarged partial sectional views of the fender around a buckling point thereof, showing the configurations before and after buckling thereof, respectively;

FIGS. 4A and 4B are graphs showing the operative characteristics of the fender, as illustrated by the relatons among the compressive loading, strain, and the amount of energy absorbed; and

FIGS. 5 and 6 are sectional Views of different embodiments of the present invention, shown by lateral Sections thereof, respectively.

Referring to FIGS. 1 and 2, a fender comprises an elongated flat shock-receiving portion 1, a pair of mounting portions 2, 2' disposed in parallel with said shockreceiving portion 1 at either side thereof, and a pair of shock-absorbing portions 3, 3' connecting said shockreceiving portion 1 to said mounting portions 2, 2', respectively, so that the fender has an arch-like lateral crosssection.

Each shock-absorbing portion 3 or 3' has a buckling point P or P' formed on the inner surface thereof, each said shock-absorbing portion having a lower portion eX- tending uprightly from said mounting portion and an upper portion extending obliquely toward said shockreceiving portion, said buckling point forming the boundary of said lower and said upper portions. Each mounting portion 2 or 2' has a reinforcing iron plate 5 or 5' embedded therein. Bolt holes 441, 4b, 41', elongated in the longitudinal direction of the fender, are bored on the mounting portions 2, 2', so that fastening bolts (not shown) anchored in quay wall structures may fit in the bolt holes 4a to 4f for securing the fender to the quay wall by using siutable nuts.

FIG. 3A shows structure of the buckling point P or P'. Each shock-absorbing portion 3 or 3' has a comparatively thick portion adjacent to the shock-receiving portion 1 and a comparatively thin portion adjacent to the mounting potion 2 or 2', and the buckling point P or P' is located on the boundary between the comparatively thick and the comparatively thin portions. In a preferred embodiment of the present invention, if the height of the fender is assumed to be H, as measured from the bottom of the mounting portion 2 or 2', to the flat top of the shockreceiving portion 1, the height of the buckling point P or P' is 0.2H to 0.5H, as measured from the bottom of the mounting portion, and the distance between the two buckling points P and P' should be 0.4H to 0.8H. In the particular embodiment, as depicted in FIGS. 1 and 2, the comparatively thin portions of the shock-absorbing portion 3 or 3' extend uprightly from the mounting portion 2 or 2', while the comparatively thick portions of each shock-absorbing portion extend obliquely towards each other and join to the shock-receiving portion 1, so as to intensify the effectivity of the buckling points P, P' of the aforesaid construction.

The operative characteristics of the fender, especially the relations among the strains, compressive load, and the amount of energy absorbed, will now be described in further detail, referring to FIG. 4. In the figure, curves A, a, curves B, b, and curves C, c represent operative characteristics of a fender according to the present invention, a trapezoidal hollow fender, and a cylindrical fender, respectively.

The fender according to the present invention has a reactive force smaller than that of the trapezoidal hollow fender. For instance, the reactive force R of the fender, according to the present invention, for absorbing a given amount of energy E is smaller than the corresponding reactive force R of the trapezoidal hollow fender for absorbing the same amount of energy E As compared With cylindrical fenders of circular cross section, the fender of the present invention has a higher reactive force, as long as the amount of energy to be absorbed is small, yet the amount of energy absorbed by the fender of the invention is considerably larger than that of the aforesaid eylindrical fender. If the cylindrical fenders should be required to absorb the same amount of energy E the reactive force R of such known fenders becomes larger than that of the present invention. According to the present invention, buckling points were provided on the inside surface of the shock-absorbing portion by making the cross section of the fender in an arch-like shape, rather than in a circular or rectangular shape. Thus, in the fender of the invention, the buckling takes place for comparatively small strain, so that the reactive force curve of the fender of the invention rses only when the strain has increased to a noticeably large magnitude.

FIGS. 5 and 6 illustrate different embodiments of the present invention. The fender of FIG. 5 has a flat shockreceiving portion 1 and a pair of shock-absorbing portions 3, 3' issuing from either longitudinal edge of the shock-receiving portion 1, so as to form a certain angle between the planes of the two shock-absoring portions 3, 3'. This construction is particularly useful for the case in which only the amount of energy absorbed in concerned but the reactive force need not be restricted so severely. The embodiment, as shown in FIG. 6, has a shock-receiving portion including an arcuate top, which is suitable for the case in which the magnitude of the reactive force should be restricted. The arcuate Configuration of the shock-receiving portion results in that the amount of energy absorbed is substantially independent of the difference of access angle of the ship towards the fender.

As described in the foregoing, the fender according to the present invention has very stable operative characteristics. In addition, non-circular construction of the fender simplfies the manufacture thereof, and at the same time, the dispersion of the thickness of the shock-absorbing portions can be eliminated. With the elongated bolt holes, the fender can be easily aligned and secured to the quay wall, even when anchor bolts for securing the fender are not installed so accurately, by allowing the adjustment of the fender position in the longitudinal direction thereof. Furthermore, the fender of the present invention can be also secu red to a curved wall surface.

One or more of the fenders of the present invention can be disposed on the straight or Curved portions of walls of quays, piers, jetties, harbors, oil-rigs, dolphins, etc.

It is apparent to those skilled in the art that the detailed construction and parts of the aforesaid embodiments can be modified and changed in various manners without departing from the scope and spirit of the present invention.

What is claimed is:

1. An arch-shape fender having a lateral cross section comprising,

an elongated shock-receiving portion;

a pair of mounting portions, disposed below said shockreceiving portion in parallel and in symmetry therewith and spaced by a distance larger than the Width of said shock-receiving portion; and

a pair of shock-absorbing portions, Connecting said shock-receiving portion to said mounting portions, each having a comparatively thick portion adjacent to said shock-receiving portion, a comparatively thin portion adjacent to said mounting portion, and a buckling point disposed on the inner surface of said shock-absorbing portion at the boundary between said comparatively thick and said comparatively thin portions thereof;

said shock-receiving portion having a tip away from the bottom of said mounting portions by a vertical distance of H, said buckling points of said shock-absorbing portions being away from said bottom of said mounting portions by a vertical distance corresponding to 0.2H to 0.5I-I and spaced each other by a distance corresponding to 0.4H to 0.8H.

2. An arch-shape fender according to claim 1, wherein said shock-receiving portion has a flat top, and each said shock-receiving portion has a lower portion extending uprightly from said mounting portion and an upper portion extending obliquely toward said shock-receiving portion, said buckling point forming the boundary of said lower and said upper portions.

3. An arch-shape fender according to claim 1, wherein said shock-receiving portion has a flat top, and said shockabsorbing portions issue from longitudinal edges of said shock-receiving portion and extend obliquely outwards to said mounting portions.

4. An arch-shape :fender according to claim 1, wherein said shock-receiving portion has an arcuate convex top, and said shock-absorbing portions issue from longitudinal edges of said shock-receiving portion and extend obliquely outwards to said mounting portions.

References Cited UNITED STATES PATENTS 3,197,189 7/1965 Pernper et al 267-1 3,418,815 12/1968 Kumazawa 267-1 JAMES B. MARBERT, Primary Examiner 

